Truncated Cone Heart Valve Stent

ABSTRACT

A heart valve stent having a section with a heart valve implant and several proximally disposed tissue anchors, also comprising a plurality of anchoring threats, each with a proximate end fastened to the stent or valve and a distal end attached to tissue within a heart chamber to provide tension between the heart chamber tissue and the stent.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the right of priority pursuant to 35 USC §120 toSer. No. 12/677,958, filed Sep. 9, 2010, pursuant to 35 USC §199(a) toPCT/DE2008/001515, filed Sep. 10, 2008, and to parent German applicationno. 10 2007 043 830.5, filed Sep. 13, 2007, each of which isincorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

No federal government funds were used in researching or developing thisinvention.

BACKGROUND Field of Invention

The invention refers to a valve stent with a section equipped to receivea heart valve implant and several of proximally disposed anchoringelements.

Such heart valve stents are known in various forms for the replacementdysplastic and degenerated heart valves. Thereby, the surgicalimplantation of heart valve prostheses is regularly accomplished in thecardioplegic heart. The old, functionally degenerated heart valve isresected and the new, implantable heart valve is sewed in.

However, when the mitral valve is affected, one tries, as far aspossible, to maintain the old valve in spite of its malfunctioning sothat the entire dynamic mitral valve apparatus is not disturbed. Thereason for this is that, for instance, the chordae tendineae, which areattached to the mitral valve are very important for ventricularfunction. Therefore, they should preferably not be removed from the oldmitral valve.

Ideally, the mitral valve (in case the old valve cannot bereconstructed) will be pushed aside as far as possible to make room fora new valve. Space does not play such an important role as compared tothe aortic annulus which can be more easily stenosed (i.e., duringdisplacement of the old aortic valve for sole percutaneousimplantation).

The chordae tendineae of the mitral valve shall be, if possible,structurally maintained to preserve the ventricular geometry and henceof the left ventricle or achieve optimal function of the left chamber asfar as possible. Therefore, a best possible function of the left chamberis obtained and achieved. Of significant relevance is that the anteriormitral valve leaflet is not pushed aside into the free space toward theleft ventricle, but rather that it is attached to the mitral annulus sothat a press forward of the anterior leaflet into the left ventricularoutflow tract (LVOT) is avoided (“sam” phenomenon: systolic anteriormovement). This is extremely important, because otherwise a left heartdecompensation (massive dysfunction of the left ventricle) could rapidlyoccur.

Surgically the old mitral valve is attached to the old annulus so thatthere is a free flow of blood through the valve and both adjacent heartchambers. After pushing aside (attachment of the valve onto the annulus)the heart valve prosthesis is surgically implanted into the annulus.

This extensive method mandatorily takes place with the help of a heart-and lung-machine. For high risk patients it is usually not used andminimally invasive and percutaneous methods to perform the implantationof a heart valve are sought.

In this context, the German patent DE 195 46 692 C2 and thecorresponding EP 1 469 797 B1 is known. This patent describes aself-expanding heart valve prosthesis for the implantation into a humanbody using a catheter system with a heart valve and a foldable,valve-connected and expanding stent. Such a self-expanding heart valveprosthesis can be directed through the femoral artery with the help of acatheter based system to the area of cardiac implantation. After thestent reaches the area of implantation, it can be successively unfolded.Along its long axis, the stent is composed of several, at angles to eachother, self-expanding segments that are unfolded gradually. Afterexpansion, the heart valve prosthesis can be anchored with the supportof hooks at least in the respective blood vessel close to the heart.

Another apparatus for the fixation and anchorage of heart valveprostheses is described in the German Patent 100 10 074 A1 whichfundamentally consists of wire-like elements attached together.Different brackets are hereby used to secure anchorage and brace a heartvalve.

Even with the known solutions there is still the danger that a heartvalve will be incorrectly implanted due to wrong positioning anddeficient angular adjustment of the heart valve prosthesis.

Improved positioning and angular alignment for the aortic valve can bereached by the stent described in the European Patent EP 1 469 797 B1which consists of supportive holders which can be inserted into theaortic pouches and create a defined distance to the aortic valve. Beyondthis, the possibility exists to halt a failed implantation of a heartvalve prosthesis and to push the valved stent (“a valve integrated intoa stent”) back into the catheter delivery system (more precisely the“cartridge”). Thereby, it is possible that the stent can again slide outwhen good positioning for the valved stent has been reached. Thus, thevalved stent can be taken in and out until the optimal positioning hasbeen achieved (“sliding technique”).

A much larger problem for the optimal positioning of the new heart valvein the stent (alternatively valved stent) still exists in the following:in most cases the old, native valve will not be eliminated by theabove-described technique of implantation.

This leads to the fact that the new valve which will be pressed into(partly squashed into) the old, deformed valve will be transformed intothe original form. The reason for this is that the location ofimplantation for the valved stent is affected by the morphology, theshape and consistency of the old native valve (for instance by sclerosisor calcification of the native valve).

Therefore, the old annulus of the valve with the corresponding changedvalves pouches determines to what extent and where the native valve willunfold and whether its form can develop. Hence, for the optimal functionof the valve and maintenance of the atrial and ventricular function notonly the anchorage/positioning is important, but also the fitting of thevalve stent into the neo-annulus (old valve annulus with old valveshapes it) and with it the pushing back of the old valve.

Based on the fact that there are known problems of the valved stents,the challenge of this intervention is to produce a heart valved stent,especially a mitral valved stent, for minimally-invasivetransplantation, which preferably facilitates the natural functioning ofthe heart.

Referring to the invention, this problem will be solved with the heartvalved stent and its features from claim 1. The subclaims provideadvantageous designs for setting up the intervention.

The basic idea of the invention is to produce a heart valve stent whichestablishes the anatomic requirements for the natural exertion of thefunction—like a healthy heart. In the process, the invention-relatedheart valve stent with its self-expanding, foldable embodimentestablishes a minimally-invasive operation which assures an exactpositioning and secure fixation of the valve stent. Thereby, a tensionbetween the mitral valve and ventricle similar to the natural tension ofthe chordae tendineae is generated, and at the same time it will beprovided that the valve parts of the old mitral valve (especially theanterior mitral valve leaflet) will not disturb the flow rate of theblood.

Therefore, it is intended that the valve stent, according to theinvention, is catheter-inserted into one of the heart chambers or intothe adjacent large vessels of the heart, then unfolded in one of theheart chambers, whereupon its anchoring elements are fixed in thetissue. Finally, the stent is fixed at its opposed, subvalvular wall ofthe heart chamber under development of a tension between the wall of theheart chamber and the proximal, supravalvular, fixed anchoring elementswith anchoring sutures (hereafter referred to as neo-chordae).

The fixation of the anchoring sutures in the distal wall of the heartchamber exhibits a thrust bearing to the proximal anchoring elementswhich will be established by a joint or another element acting as athrust bearing. This counter bearing can be preferentially designed alsoas an adjusting element for the length of the sutures.

Advantages of the heart valve stents which according to the interventionare the exact and easy fixation of the heart valve stent and improvedcontractility of the heart in minimally invasive operations incomparison with customary valve stents.

Preferentially, the axially, relatively to the longitudinal axis,arranged anchoring sutures are fixed according to the invention (thevalve stent) with one end to the annulus of the heart valve implant, sothat after development of a tension between the stent and the wall ofthe ventricle, the positioning and the angular arrangement of the valvecan be directly impacted. The anchoring sutures can also be fixed at thedistal part of the circumference of the valve stent. The connectionbetween the anchoring sutures and the stent has to be conducted so thata tension which should run fundamentally in an axial direction relativeto the long axis of the stent and is formed between the proximalanchoring elements and the distal counter bearing.

According to another preferential design of the invention, the anchoringsutures (neo-chordae) have elements to adjust the length of theanchoring sutures so that through the length of the anchoring sutures acertain tension between the heart valve stent and the heart wall can beregulated.

Thereby, an adjusting element, for example, for the individual length ofsutures or for all sutures together can be allowed for. The adjustingelement for the length of sutures is preferably designed small and can,for instance, be constructed in such a manner that this element shortensthe suture to the desired length by rolling up the excess thread.

The construction of the elastic anchoring sutures along the axis arealso preferred so that they are able to react to heart contractionswithout having too sutures that might negatively affect the heartfunction. Here the suture length should be selected so that theelasticity is not sacrificed due to the tension between the anchoringelements and the heart wall.

After adjusting the counter bearing of the adjusting element to thelength of sutures, a notably beneficial design is made so that also are-adjustment of the tension between the anchoring elements and thecounter bearing, i.e. a re-tensioning of the anchoring sutures ispossible without opening the heart.

Especially favored is the structure of the mitral valve stent which isfundamentally oval or u-shaped in the plane of the mitral valve annulusso that no pressure to the LVOT (left ventricular outflow tract) and/oraortic annulus is exerted. Therewith damage to the hearts function isstopped (Ma L, Tozzi P, Huber C H, Taub S, Gerelle G, von Segesser L K.Double-crowned valved stents for off-pump mitral valve replacement. EurJ Cardiothorac Surg. 2005 Aug; 28 (2):194-8; discussion 198-9.).Additionally, the subvalvular apparatus also completely retains itsnatural anatomy and is not compromised (Boudjemline Y, Agnoletti G,Bonnet D, Behr L, Borenstein N, Sidi D, Bonhoeffer P. Steps toward thepercutaneous replacement of atrioventricular valves, an experimentalstudy. J Am Coll Cardiol. 2005 Jul 19; 46 (2) i360-5).

This valve stent has for the natural mitral valve apparatus a completelyadapted, exceedingly nestled form so that this conically tapered(cranial-caudal axis) not entirely circular (oval-like in thetransversal axis) valve stent is able to attach to and abut to thenatural form of the mitral valve. In the area of the anterior mitralvalve annulus, the valve stent is flat and exerts almost no pressure onand does not constrict the LVOT. In the area of the posterior mitralvalve annulus, it is oval and replicates a form like the posteriorannulus. This valve stent forms a thin, restricted along the length(cranial-caudal) structure which in its form aligns completely to themitral valve and thus in the area of the natural mitral valve annuluslooks like a negative impression of it. In fact, the valve stentcontacts the old mitral valve and the annulus, but leaves their anatomycompletely unchanged.

In the following the invention will be closely elucidated by means ofthe attached figures representing the particularly preferred executionexamples. It shows:

FIG. 1 a favored execution example of the valve stent according to theinvention in a schematic lateral view;

FIG. 2 the demonstrated execution example in FIG. 1 with top view fromabove;

FIG. 3 top view on several especially preferred valve stents accordingto the invention;

FIG. 4 a top view from an execution example from below;

FIG. 5 a schematic view which explains the minimally-invasivetransplantation of the mitral valve stent according to the invention ina first phase of insertion of the mitral valve stent into the locationof transplantation;

FIG. 6 a schematic view for the demonstration of the minimally-invasivetransplantation of the mitral valve stents according to the invention ina second phase after positioning of the mitral valve;

FIG. 7 a schematic view for demonstration of the minimally invasivetransplantation of the mitral valve stent after completion of thefixation of the anchoring sutures outside of the apex of the ventricularheart wall;

FIG. 8 a schematic view of an alternative, intra-cardiac fixation of theanchoring sutures in the area of papillary muscles;

FIG. 9 a schematic view of a heart valve stent which is fixed in theaortic annulus according to the invention;

FIG. 10 a schematic view of a heart valve stent which is fixed in thepulmonary position according to the invention;

FIG. 11 a schematic view of a heart valve stent which is fixed in thetricuspid position according to the invention;

FIG. 12 an especially preferred execution example of the valve stent(according to the invention) in a schematic lateral view without heartvalve and anchoring sutures; and

FIG. 13 a schematic dorsal, intra-cardiac view of a heart valve stentwhich is fixed in the mitral position according to the invention.

FIGS. 1 to 11 indicate the stent according to the invention for theimplantation and fixation of heart valve prostheses in different viewsto show the configuration of the stents and the spatial relations ofindividual parts of the stent to each other in an unfolded (FIGS. 1-4and 6-11) and in a folded condition (FIG. 5).

FIG. 1 shows a foldable mitral valve stent 10 according to the inventionin a perspective lateral view. The stent 1-0 exhibits mainly threeparts: proximally (supravalvularly) on stent 10 there are severalserrated, arched anchoring (FIG. 3) elements circularly arranged whichare able to anchor supravalvularly (respectively atrially) the valvestent 10 in an implanted condition. The preferable stent body 30flattened to the LVOT is distally adjoined and is conical and in crosssection ovally shaped (compare FIG. 2).

The stent body 30 forms a basket- or trapezoid-like figure which nestlesto the mitral valve annulus and extends in the direction of the leftventricle. This stent 10 is held in the atrium due to itsconically-tapered form and due to the atrial anchoring elements 20. Abi- or tri-leaflet valve 50 can be integrated into the stent body 30.

At the distal part of the stent body 30 (to the direction of the leftventricle) there are anchoring sutures 40 which are distally equipped tothe stent body 30 for the anchorage of the entire stent 10. Theseanchoring sutures 40 provide for an anchorage in the opposed wall of theventricle or for instance in the area of the papillary muscles 30(proximal, medial or distal part of the papillary muscle); compare FIGS.7 and 8. With the help of a adjusting element to regulate the length ofsutures 70, these anchoring sutures 40 can be positioned and adjusted tothe optimal length so that the heart valved stent 10 can be fixed andanchored.

FIG. 2 indicates the stent 10 in a top view. Thereby, it can bedistinguished that stent 10 forms a neo-annulus, alternatively a stentbody 30 in which the heart valve prosthesis 50 can be implanted and inwhich it can be fixed. Furthermore, it can be recognized that theinvention-like stent 10 can be shaped asymmetrically in relation toseveral supravalvular (atrial) stent brackets 20.

This can be identified by the fact that the stent body 30 is oval-likeand flattened on one side as seen in this figure, so it (the stent body30) can be installed with its flattened side towards the direction ofthe LVOT. This flattening has the consequence that no pressure on thisside towards the LVOT and towards the aortic valve can be exerted fromthe self-expanding stent in case the stent 10 is used, i.e. in themitral position. Further favored embodiments of the stent 10 areindicated in FIG. 3 according to the invention.

FIG. 4 demonstrates the invention-pertaining stent 10 from a bottomview. From this it is obvious that the diameter of the atrial part tothe ventricular part of the stent body 30 becomes smaller so that thislooks like a truncated cone from the lateral view (compare FIG. 1). Theanchoring elements 20 as well as the stent body 30 can be upholsteredwith cloth (i.e. synthetics, pericardium, PTFE or Goretex, etc.) toachieve better sealing between the heart valve prosthesis 50, stent body30 and the surrounding heart structure. This sealing membrane istapered/alternatively upholstered between the heart valve prosthesis 50,the stent body 30 or onto the atrial stent struts 20 to achieve optimalsealing of the valve between both heart chambers.

In FIGS. 5 to 7 and 8, the retrograde trans-apical implantation of thevalved stent is described. The retrograde trans-aortic as well as theantegrade trans-atrial approach can stent above the old mitral annulusis shown in FIG. 5. A slow unfolding (preferred self-expanding) of theatrial anchoring elements 20 can be started after successful orientationwith support of labeling at the valve stent 10 (not shown). Thepositioning in the left atrium should be done in that way that theflattened side of the stent body 5 is turned towards the direction ofthe LVOT (aortic valve). The stent will be further expanded.

FIG. 6 indicates the expanded valve stent 10 in theleft-atrio-ventricular in-flow tract. Anchoring sutures 40 are adjustedin or outside the wall of the heart and later—as shown in FIG. 7—theywill be fixed with the support of the thrust bearing 80 which isfavorably designed as an adjusting element for the length of sutures.During the adjustments for the length of the anchoring sutures 40,visualization of the mitral valve apparatus (i.e. Echo, CT, NMR) iscarried out so as to optimally pull the annulus of the new stent 10toward the ventricular wall, paravalvular leakage no longer exists, thestent 10 can be fixed in a good manner, and the mitral valve annulusand—apparatus support advantageously the left ventricular function.

Alternatively to FIG. 7, the anchoring sutures 40 can also be fixed atthe papillary muscles (see FIG. 8) so that these sutures 40 representthe neo chordae and take 20 over the function of the functionlesschordae tendineae. The fixation of the anchoring sutures 40 at the wallof the heart in each case result from a thrust bearing 80 which can bedeveloped as a knot or also as an independent element. It is alsopossible that the ventricular anchoring sutures 40 are not only affixedto the stent body 30, but also at the integrated valve itself. Thecaudal anchoring sutures 40 can also be fixed at any other point of theventricle.

FIG. 7 shows the accomplished positioning and fixation of the stent 10.After the length and location of the single anchoring sutures 40 hasbeen determined, these anchoring sutures 40 will be fixed with thesuture-length adjusting elements 70, for instance, in the leftventricular wall. The suture-length adjusting element 70 is used for theoptimal calibration of the length and position of the valve stent 10 andtherefore for the valve prosthesis 50. Different sutures 40 can exhibitdifferent length and fixing positions in the ventricle.

FIGS. 9 to 11 demonstrate additional examples for the application of thevalve stent 10 according to the invention, whereas the stent 10 isreadjusted to the particular anatomy (for the aortic- and pulmonaryvalve position a rather circular form (compare FIG. 3) and for thetricuspid position a rather oval form).

FIG. 12 shows an especially preferred designed execution example of thevalve stent pertaining to the invention in a schematic lateral viewwhich is shown without heart valve and anchoring sutures for a betterclearness. For clarification in FIG. 12 of the positioning of the valvestent in situ, FIG. 13 demonstrates a schematic, dorsal, intra-cardiacview of a fixed heart valved stent in the mitral position according tothe invention. Note the good alignment of the valved stent with the leftatrial environment. Distances between the left atrial wall/mitralannulus and the valved stent are avoided. Heart valve and anchoringsutures for the ventricular apex have been omitted for simplification.

1. A heart valve stent, shaped as a truncated cone, comprising: a stentbody section with a heart valve implant; a plurality of tissue anchorsattached to a proximal end of the stent body section in a radialpattern; and a plurality of anchoring threads, each such thread having aproximal end attached to the stent and a distal end anchored to theopposite wall of the heart chamber via a tissue anchor.
 2. The heartvalve stent of claim 1, further comprising at least one suture-lengthregulatory element for adjusting the length of at least one of theplurality of anchoring threads.
 3. The heart valve stent of claim 1,further comprising a plurality of serrated, arched or triangular atrialanchoring elements radiating outward from the upper rim of the stentbody section.
 4. The heart valve stent of claim 1, further comprisingwherein the heart valve implant is integrated within the lumen of thestent body section near or at the proximal end of the stent bodysection.
 5. The heart valve stent of claim 4, wherein the heart valveimplant further comprises one of the group of a circular, oval-shapedand u-shaped annulus.
 6. The heart valve stent of claim 4, furthercomprising wherein the heart valve implant is a mitral valve.
 7. Theheart valve stent of claim 4, further comprising wherein the heart valveimplant is a tricuspid valve.
 8. The heart valve stent of claim 4,further comprising a sealing membrane between the heart valve implantand the stent.
 9. The heart valve stent of claim 1, wherein the stentbody is further comprised of a cross-hatching of metal wire, includingbut not limited to the group of diamond-shaped hatching, loop-shapedhatching, or a similar pattern.
 10. The heart valve stent of claim 9,further comprising wherein the wire is made from a shape memory alloy.11. The heart valve stent of claim 9, wherein the stent body is foldableand self-expanding.
 12. A heart valve stent, shaped as a truncated cone,comprising: a foldable, self-expanding stent body section with a heartvalve implant, wherein the stent body section is comprised of across-hatching of metal wire made from a shape memory alloy, includingbut not limited to the group of diamond-shaped hatching, loop-shapedhatching, or a similar pattern; a plurality of serrated, arched ortriangular atrial tissue anchors attached to the proximal end of thestent body section in a radial pattern; said heart valve implantintegrated within the lumen of the stent body section at or near theproximal end of the stent body section; said valve implant furthercomprising one of the group of a circular, oval-shaped or u-shapedannulus and either a mitral valve or a tricuspid valve; a sealingmembrane between the heart valve implant and the stent; a plurality ofanchoring threads, each such thread having a proximal end attached tothe stent and a distal end anchored to the tissue within the heartchamber via a tissue anchor; and at least one suture-length regulatoryelement for adjusting the length and tension of at least one of theplurality of anchoring threads.